губа не дура

(у кого)

прост.

smb. knows a good thing when he sees it; smb. knows what's good for him; smb. knows what is what; smb. knows what he is about; smb. is no fool when it comes to his belly; cf. he knows on which side his bread is buttered

[Собакевич] опрокинул половину бараньего бока к себе на тарелку, съел всё, обгрыз, обсосал до последней косточки. "Да, - подумал Чичиков, - у этого губа не дура". (Н. Гоголь, Мёртвые души) — Sobakevich... overturned half the side of mutton onto his plate, and ate it all up, gnawing clean and sucking every last bit of a bone. 'Yes,' reflected Chichikov, 'this fellow is no fool when it comes to his belly.'

- Ну, брат, здорово кутил, по-сибирски. Тоже губа не дура, какую девчонку облюбовал. (Л. Толстой, Воскресение) — 'There, old fellow, that was something like! Real Siberian fashion! He knew what he was about, no fear! That's the sort of wench for me.'